Antitubercular, rifamycin derivative
Brand names: Mycobutin
Updated · Methodology
Second line
Rifabutin is second-line antitubercular in standard 4-drug regimen (replacing rifampicin) in HIV-positive patients on ART or transplant recipients. 2024 recommends rifabutin when rifampicin causes unacceptable drops in co-administered drug levels.
Sources
ICD-10: A15 · ICD-11: 1B10
Inhibits DNA-dependent RNA polymerase of mycobacteria and bacteria. Spectrum is similar to rifampicin, but CYP3A4 induction is 2–3 fold weaker – hence preferred with antiretrovirals and immunosuppressants. Additional advantage – activity against Mycobacterium avium complex.
Used when necessary. Safety better studied outside pregnancy.
Passes into milk. Breastfeeding possible with infant monitoring.
Reference information, not a clinical decision. Discuss feeding pauses or changes with your physician or an IBCLC.
4 pairs found. Sorted from critical to minor.
Mechanism
The interaction runs both ways. Voriconazole inhibits CYP3A4, the liver enzyme that breaks down rifabutin. With voriconazole 400 mg twice daily, the rifabutin area under the curve (AUC) rose by 331% and peak concentration by 195%. Rifabutin in turn speeds up voriconazole metabolism: at the usual 200 mg twice daily, voriconazole AUC fell by 78% and peak concentration by 69%. At 350 mg twice daily, voriconazole peak concentration was close to the usual level (4% lower), but AUC stayed 32% lower than with 200 mg without rifabutin. At 400 mg twice daily, voriconazole peak concentration and AUC almost doubled.
Symptoms
Excess rifabutin can show as uveitis: eye pain and redness, photophobia, blurred vision. Neutrophil and, less often, platelet counts fall, which can lead to fever, infections or bruising. Too little voriconazole shows as a fungal infection that does not respond to treatment: fever persists and lesions in the lungs or other organs do not regress.
Management
The combination is contraindicated in the US labels of both voriconazole and rifabutin (US Food and Drug Administration, ). In Europe it is not contraindicated, but avoid it unless the benefit outweighs the risk (voriconazole SmPC, European Medicines Agency, ; rifabutin ficha técnica, Spanish Agency of Medicines, AEMPS). If there is no alternative to rifabutin, raise the voriconazole maintenance dose: orally from 200 to 350 mg twice daily (from 100 to 200 mg twice daily in patients under 40 kg), or intravenously to 5 mg/kg twice daily (voriconazole SmPC, EMA). Throughout co-administration, closely monitor the full blood count and adverse effects of rifabutin, especially uveitis (voriconazole SmPC, EMA). If uveitis is suspected, refer the patient to an ophthalmologist and stop rifabutin if needed (rifabutin ficha técnica, AEMPS).
Sources
Mechanism
Rifabutin is a moderate CYP3A4 + P-gp inducer (2-3 fold weaker than rifampicin). Apixaban falls 30-40%. Lower risk than with rifampicin but still significant.
Symptoms
Reduced anticoagulation, thrombosis risk.
Management
If possible – warfarin to INR 2.0-3.0.
Sources
Mechanism
Clarithromycin inhibits CYP3A4. Rifabutin rises 2.5-fold – increased uveitis risk, especially in MAC infection patients.
Symptoms
Eye pain, photophobia, reduced vision.
Management
Reduce rifabutin to 300 mg/day (standard 450 mg). Regular ophthalmology review.
Sources
Mechanism
Ritonavir inhibits CYP3A4. Rifabutin rises 4-fold – severe neutropenia and uveitis risk. 2024 recommends reducing rifabutin to 150 mg three times weekly.
Symptoms
Neutropenia, uveitis within 2-4 weeks.
Management
Reduce rifabutin to 150 mg three times weekly. Weekly CBC for first month.
Sources
Verbatim lines from the interaction sections, in the language of the label
«Effect of Other Drugs on Rifabutin Pharmacokinetics: Voriconazole 400 mg twice a day for 7 days (maintenance dose) 300 mg once a day for 7 days Healthy male subjects (12) ↑ AUC by 331%, ↑ C max by…»FDA, section 7 · Open on DailyMed
«Effect of Other Drugs on Rifabutin Pharmacokinetics: Itraconazole 200 mg once a day 300 mg once a day HIV-Infected patients (6) ↑ data from a case report ↓ AUC by 70%, ↓ C max by 75%, If…»FDA, section 7 · Open on DailyMed
«Effect of Other Drugs on Rifabutin Pharmacokinetics: Posaconazole 200 mg once a day for 10 days 300 mg once a day for 17 days Healthy subjects (8) ↑ AUC by 72%, ↑ C max by 31% ↓ AUC by 49%, ↓ C max…»FDA, section 7 · Open on DailyMed
«Effect of Other Drugs on Rifabutin Pharmacokinetics: Lopinavir/FDA, section 7 · Open on DailyMed
«Effect of Other Drugs on Rifabutin Pharmacokinetics: Some drugs that inhibit CYP3A may significantly increase the plasma concentration of rifabutin. Therefore, carefully monitor for rifabutin…»FDA, section 7 · Open on DailyMed
«Effect of Other Drugs on Rifabutin Pharmacokinetics: Some drugs that inhibit CYP3A may significantly increase the plasma concentration of rifabutin. Therefore, carefully monitor for rifabutin…»FDA, section 7 · Open on DailyMed
«Effect of Other Drugs on Rifabutin Pharmacokinetics: Some drugs that inhibit CYP3A may significantly increase the plasma concentration of rifabutin. Therefore, carefully monitor for rifabutin…»FDA, section 7 · Open on DailyMed
«Effect of Other Drugs on Rifabutin Pharmacokinetics: Atazanavir/FDA, section 7 · Open on DailyMed
«Effect of Other Drugs on Rifabutin Pharmacokinetics: Azithromycin 500 mg once a day for 1 day, then 250 mg once a day for 9 days 300 mg once a day Healthy subjects (6) ↔ ↔»FDA, section 7 · Open on DailyMed
«Effect of Other Drugs on Rifabutin Pharmacokinetics: Elvitegravir/FDA, section 7 · Open on DailyMed
«Effect of Other Drugs on Rifabutin Pharmacokinetics: Darunavir/FDA, section 7 · Open on DailyMed
«Effect of Other Drugs on Rifabutin Pharmacokinetics: Ethinylestradiol (EE)/FDA, section 7 · Open on DailyMed
«Effects of Other Drugs on Ranolazine: CYP3A Inducers Do not use ranolazine extended-release tablets with CYP3A inducers such as rifampin, rifabutin, rifapentine, phenobarbital, phenytoin…»FDA, section 7 · Open on DailyMed
«CONTRAINDICATIONS: Coadministration of voriconazole tablets with rifabutin is contraindicated since voriconazole tablets significantly increase rifabutin plasma concentrations and rifabutin also…»FDA, section 4 · Open on DailyMed
«Established and Other Potentially Significant Drug Interactions: rifabutin ↑ rifabutin A rifabutin dose reduction of up to 75% (e.g., 150 mg every other day or 3 times per week) is recommended…»FDA, section 7 · Open on DailyMed
«Established and Other Potentially Significant Interactions: rifabutin ↑ rifabutin cobicistat: effects unknown darunavir: effects unknown atazanavir: effects unknown The recommended adult dosage…»FDA, section 7 · Open on DailyMed
«ANTIMICOBACTERIANOS: En pacientes que reciben la combinación con darunavir administrado de forma conjunta con ritonavir, se justifica una reducción de la dosis de rifabutina del 75 % de la dosis…»AEMPS, section 4.5 · Open on CIMA
«Established and Other Potentially Significant Drug Interactions: Antimycobacterials : rifampin rifabutin (The reference regimen for rifabutin was 300 mg once daily.) rifapentine ↓ darunavir …»FDA, section 7 · Open on DailyMed
«Tratamiento de larga duración: Sustancias que aumentan el aclaramiento de las hormonas anticonceptivas (disminución de la eficacia anticonceptiva por inducción enzimática), por ejemplo: Barbitúricos…»AEMPS, section 4.5 · Open on CIMA
«La administración de dexametasona con inductores de CYP3A4, como efedrina, barbitúricos, rifabutina, rifampicina, fenitoína, y carbamazepina puede conducir a una reducción de las concentraciones…»AEMPS, section 4.5 · Open on CIMA
«Established and Other Potentially Significant Drug Interactions: Antimycobacterial: Rifabutin ↓ rifabutin * Increase daily dose of rifabutin by 50%. Consider doubling the rifabutin dose in regimens…»FDA, section 7 · Open on DailyMed
«Potencial de interacción: No se debe usar itraconazol hasta 2 semanas después de la suspensión del tratamiento con medicamentos inductores del CYP3A4 (rifampicina, rifabutina, fenobarbital…»AEMPS, section 4.4 · Open on CIMA
«Rifabutina: Rifabutina (300 mg una vez al día) disminuyó la C máx (concentración plasmática máxima) y el AUC (área bajo la curva temporal de concentración plasmática) de posaconazol al 57 % y 51 %…»AEMPS, section 4.5 · Open on CIMA
«DRUG INTERACTIONS: Rifabutin, phenytoin, efavirenz Avoid coadministration unless the benefit outweighs the risks ( 7.1 , 7.2 )»FDA, section 7 · Open on DailyMed
«El efecto modulador enzimático del ritonavir puede ser dosis dependiente. Para algunos productos, las contraindicaciones pueden ser de mayor importancia cuando el ritonavir se utiliza como agente…»AEMPS, section 4.3 · Open on CIMA
«Established and Other Potentially Significant Drug Interactions: Antimycobacterial: rifabutin ↑ rifabutin and rifabutin metabolite Dosage reduction of rifabutin by at least three-quarters of the…»FDA, section 7 · Open on DailyMed
«Sirolimus es extensamente metabolizado en la pared intestinal y en el hígado por la isoenzima CYP3A4. Sirolimus es también un sustrato de la bomba de flujo multifármaco, la glicoproteína P (gp P)…»AEMPS, section 4.5 · Open on CIMA
«Strong Inducers and Strong Inhibitors of CYP3A4 and P-gp: Avoid concomitant use of sirolimus with strong inducers (e.g., rifampin, rifabutin) and strong inhibitors (e.g., ketoconazole, voriconazole…»FDA, section 7 · Open on DailyMed
«No se recomienda el uso concomitante de acetato de ulipristal con inductores de CYP3A4, debido a las interacciones (por ejemplo, barbitúricos [incluyendo primidona y fenobarbital], fenitoína…»AEMPS, section 4.4 · Open on CIMA
«Antibióticos: Se d ebe evitar la administración concomitante de voriconazol y rifabutina, a menos que los beneficios superen los riesgos. Se debe incrementar la dosis de mantenimiento de voriconazol…»AEMPS, section 4.5 · Open on CIMA
«Inductores e inhibidores enzimáticos: primidona, fenobarbital, rifabutina, efedrina y aminoglutetimida, pueden reducir el efecto.»AEMPS, section 4.5 · Open on CIMA
«Interacciones basadas en CYP3A: Se pueden considerar ajustes de dosis y cuando sea posible, las concentraciones séricas de los fármacos metabolizados principalmente por CYP3A se deben controlar de…»AEMPS, section 4.5 · Open on CIMA
«DRUG INTERACTIONS: Rifabutin Use With Caution Rifabutin: Concomitant administration of rifabutin and clarithromycin resulted in an increase in rifabutin, and decrease in clarithromycin serum levels…»FDA, section 7 · Open on DailyMed
«Rifabutina: Fluconazol aumenta la concentración plasmática de rifabutina, aumentando el AUC de rifabutina hasta un 80%. Se han comunicado episodios de uveítis en pacientes a quienes se les administró…»AEMPS, section 4.5 · Open on CIMA
«Effects of Other Drugs on Tacrolimus: Strong CYP3A Inducers 3 : Antimycobacterials (e.g., rifampin, rifabutin), anticonvulsants (e.g., phenytoin, carbamazepine and phenobarbital), St John's wort May…»FDA, section 7 · Open on DailyMed
«Posibilidad de que otros medicamentos afecten a la exposición de abiraterona: Se recomienda evitar los inductor es potentes del CYP3A4 (p.ej., fenitoína, carbamazepina, rifampicina, rifabutina…»AEMPS, section 4.5 · Open on CIMA
«Interacción de otros medicamentos con aripiprazol: La dosis de aripiprazol debe ser duplicada cuando se administra conjuntamente con carbamazepina. Cabe esperar que la administración concomitante de…»AEMPS, section 4.5 · Open on CIMA
«Recomendación relativa a la administración conjunta: No se observaron cambios clínicamente significativos en la exposición de azitromicina o de los medicamentos administrados conjuntamente en los…»AEMPS, section 4.5 · Open on CIMA
«Fármacos que pueden disminuir los niveles plasmáticos de carbamazepina: Antibióticos: doxiciclina, rifabutina.»AEMPS, section 4.5 · Open on CIMA
«El metabolismo de los estrógenos y progestágenos puede estar aumentado con el uso concomitante de sustancias que se sabe que inducen los enzimas metabolizadores de fármacos, específicamente los…»AEMPS, section 4.5 · Open on CIMA
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Rifabutin is evaluated for the following indications with varying evidence strength: Drug-susceptible tuberculosis (evidence tier A). See the full indication matrix with dosing and citations above on this page.
Common side effects of Rifabutin (≥ 1 in 100): Orange discoloration of body fluids, Nausea, Rash, Neutropenia, Transaminase rise. See the Safety section for uncommon and serious reactions.
Used when necessary. Safety better studied outside pregnancy.
Passes into milk. Breastfeeding possible with infant monitoring.
Rifabutin is contraindicated in: Rifamycin hypersensitivity; Active uveitis; Combination with delavirdine, rilpivirine. Full list in the Safety section.
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